Tris(pentane-2,4-dionato-O,O')vanadium

Endpoint summary

Description of key information

The parent compound Vanadium-tris-acetylacetonate is rapidly hydrolysed to 2,4 -pentanedione (CAS no. 123 -54- 6) and Vanadyl acetylacetonate (CAS no. 3153 -26 -2) in the presence of water or moisture (> 80% hydrolysis after 1h at pH 1.2, 4, 7 and 9). Hence, the half life is < 1 h under neutral and acidic conditions. Accordingly, reliable data of the hydrolysis products 2,4-Pentadione (Cas no. 123-54-6) and Vanadyl acetylacetonate (3153-26-2) or comparable inorganic Vanadium compounds are used to address the endpoint, which is entirely appropriate to draw conclusions on the repeated dose toxiciy of Vanadium-tris-acetylacetonate to mammals.

inhalation

Acetylacetonate, rat, whole body, 6 h/day, 5 days/week, 14 weeks (OECD TG 413): NOEC = 420 mg/m³: LOEC 1277 mg/m³

V₂O₅ rat, whole body, 6 h/day, 5 days/week, 90 days (OECD TG 413, GLP): NOAEC = 1 mg/m³ - VAA NOAEC = 3.8 mg/m³

V₂O₅ rat, whole body, 6 h/day, 5 days/week, 104 weeks (OECD TG 413, GLP): LOAEC (alveolar neoplasms) = 0.5 mg/m³ - VAA LOAEC = 1.9 mg/m³

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

please refer to Read-across statement attached in section 13

Reason / purpose for cross-reference:

read-across source

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

General signs of toxicity and sensory irritancy, seen at 650 ppm, were complete or partial eyelid closure, periocular, perinasal, and perioral encrustation, wetness around the urogenital area, hypoactivity, lack of coordination, paresis, ataxia, irregular gait, hypothermia, and emaciation.
At 650 ppm, all 20 females and 10 of 30 males died between the second and sixth weeks of exposure. These animals had acute degenerative changes in the deep cerebellar nuclei, vestibular nuclei and corpora striata, and acute lymphoid degeneration in the thymus.

Mortality:

mortality observed, treatment-related

Description (incidence):

At 650 ppm, all 20 females and 10 of 30 males died between the second and sixth week of exposure. The earliest death was after 9 days of exposure.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weights of the 650-ppm males were reduced throughout the 14-week exposure period, but there was considerable weight increase during the 4-week recovery period. However, final weights were still statistically significantly below those for the control males. Before death, body weights of the female rats of the 650-ppm group were considerably reduced. Also, females of the 307-ppm group had slight, but statistically significant, decreased body weight gains for study Days 45 through 121. However, at the conclusion of the 4-week recovery period, the difference between the absolute body weight means for the control and 307-ppm female rats was not statistically significant. Body weights of the 101-ppm-exposed rats were similar to the controls.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Even though test substance was administered via inhalation, no treatment-related alterations in food and water intake were observed at the conclusion of the 14 week exposure regimen.

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

Even though test substance was administered via inhalation, no treatment-related alterations in food and water intake were observed at the conclusion of the 14 week exposure regimen.

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

For the 650-ppm males and the 307-ppm females, the respective mean erythrocyte counts were 11 and 4% below control values. The decrease in red blood cell count was accompanied with slight increases in MCV and MCH and a mild decrease in hematocrit. The white blood cell count was increased in the 650-ppm male rats, due to an increase in lymphocytes. There was recovery from these effects by the end of the 4-week postexposure period.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Clinical chemistry determinations which deviated from controls were an increase in urea nitrogen and alkaline phosphatase activity, and a decrease in creatinine, calcium, and aspartate aminotransferase (AST) activity in the 650-ppm males. Serum calcium was also decreased in males and females of the 307-ppm group. Although a mild increase in alkaline phosphatase activity persisted in the 650-ppm recovery male rats, the remaining serum chemistry values were similar to control values, indicating reversibility of effects.

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Urinalysis showed minimal alterations in males, which included low pH (6.0 vs 7.0 in controls) at 650 ppm, and slightly increased bilirubin and urobilinogen at 650 and 307 ppm. These alterations in urine parameters were not found at the end of the postexposure observation period.

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

Neurobehavioural effects were observed (see neuropathological findings).

Immunological findings:

effects observed, treatment-related

Description (incidence and severity):

Thymic lesions, consisting of acute lymphoid degeneration and atrophy, were observed in 7 of 10 male and 13 of 20 female rats that died during the 14-week exposure regimen. They were not present in survivors. Dermatitis, dermal necrosis, and in a few cases, cellulitis were seen in the skin and subcutis of the heads of 5 male and 8 female rats that died, but not in survivors. The inflammatory infiltrate was predominately of polymorphonuclear leukocytes and mast cells.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

After 14-weeks of 2,4-PD vapor exposure a statistically significant decrease in most absolute organ weights was observed for the 650-ppm males, but organ weights relative to body weight had increased. Organ weights of the 101- and 307-ppm groups were unaltered, except for absolute lung weights of the females which were slightly increased at 101 and slightly decreased at 307 ppm.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Thymic lesions, consisting of acute lymphoid degeneration and atrophy, were observed in 7 of 10 male and 13 of 20 female rats that died during the 14-week exposure regimen. They were not present in survivors. Dermatitis, dermal necrosis, and in a few cases, cellulitis were seen in the skin and subcutis of the heads of 5 male and 8 female rats that died, but not in survivors.

Neuropathological findings:

effects observed, treatment-related

Description (incidence and severity):

The brain lesions observed in 7 of 10 male and 18 of 20 female rats that died during the exposure regimen took the form of acute degenerative changes in the vestibular nuclei, deep cerebellar nuclei, and corpora striata. The lesions consisted of peracute to acute areas of pallor and vacuolation in the neuropil. Within these foci were nuclear pyknosis and karyorrhexis, and the presence of macrophages with vacuolated cytoplasm. The degree of vacuolation and macrophage infiltration was greatest in the deep cerebellar and vestibular nuclei. These brain lesions were bilaterally symmetrical. Of the surviving males of the 650-ppm group, 7 of 5 had gliosis with or without malacia in the deep cerebellar nuclei, vestibular nuclei, and corpus striatum. Gliosis was most extensive in the deep cerebellar and vestibular nuclei. Many of the cells had irregular or rod-shaped nuclei typical of microglia, but others resembled astrocytes. Multifocal areas of microscopic mineralization, hemosiderosis, and neuronal degeneration were evident. No degenerative changes were seen in the spinal cords of the 650-ppm exposed animals. Transmission electron microscopic evaluation of sciatic nerves from the 650-ppm group did not produce any evidence of a peripheral neuropathy.
In addition, neurobehavioural findings were are follows:


Duration of exposure regimen (months)
Observation 1 2 3 3+1 month recovery

Tremors 1/26* 0/20 0/20 0/5
Impaired gait 4/26 0/20 2/20 0/5
Paresis 4/26 0/20 0/20 0/5
Lacrimation 2/26 1/20 0/20 0/5
Hypothermia 3/26 0/20 0/20 0/5
Abnormal surface righting 2/26 0/20 0/20 0/5
Abnormal midair righting 6/26 3/20 4/20 0/5
Abnormal wire grasping 4/26 0/20 0/20 0/5
Abnormal body tone 6/26 0/20 0/20 0/5
Abnormal limb rotation 3/26 0/20 0/20 0/5
Dilated pupils 6/26 0/20 0/20 0/5
Decreased breathing rate 2/26 0/20 0/20 0/5
Decr. locomotor activity 6/26 0/20 0/20 0/5
Absence of corneal reflex2/26 0/20 0/20 0/5
Abs. of tail pinch resp. 3/26 0/20 0/20 0/5
Abs. of audit. startle resp. 6/26 0/20 0/20 0/5
* No. affected/No. examined.

No effects were observed in the control rats or rats exposed to 101 or 307 ppm.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Light microscopy did not reveal any abnormalities in tissues removed from the animals of the 101- and 307-ppm groups. However, for the 650-ppm animals there were noteworthy histopathologic features in brain, thymus, skin, and nasal mucosa.

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The nasal mucosa showed mild multifocal squamous metaplasia at the anterior portion of the nasal cavity, in both the maxillary and nasal turbinates. This change was seen in 9 of the 10 animals exposed to 650 ppm which were sacrificed at the end of the 14-week exposure period, but was present in only one of five and with reduced severity following the 4-week recovery period. The nasal mucosa was normal in female rats exposed to 307 ppm of 2,4-PD vapor.

Other effects:

no effects observed

Dose descriptor:

NOEC

Effect level:

101 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

behaviour (functional findings)

body weight and weight gain

clinical biochemistry

clinical signs

food consumption and compound intake

gross pathology

haematology

histopathology: neoplastic

immunology

mortality

neuropathology

ophthalmological examination

organ weights and organ / body weight ratios

urinalysis

water consumption and compound intake

Dose descriptor:

LOEC

Effect level:

307 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

haematology

urinalysis

Key result

Dose descriptor:

NOEC

Remarks:

calculated from ppm (see 'Overall remarks')

Effect level:

420 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

behaviour (functional findings)

body weight and weight gain

clinical biochemistry

clinical signs

food consumption and compound intake

gross pathology

haematology

histopathology: neoplastic

immunology

mortality

neuropathology

ophthalmological examination

organ weights and organ / body weight ratios

urinalysis

water consumption and compound intake

Key result

Dose descriptor:

LOEC

Remarks:

calculated from ppm (see 'Overall remarks')

Effect level:

1 277.12 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

haematology

urinalysis

Critical effects observed:

no

Conclusions:

The repeated inhalation exposure of acetylacetonate by vapour atmospheres for a period of 14 consecutive weeks at target concentrations of 100, 300 and 650 ppm produced treatment-related changes at the two higher concentrations. On this basis, a ‘No Observed Effect Concentration’ (NOEC) of 420 mg/m3 could be derived. The lowest effect concentration was 1277.12 mg/m3. This result is also valid for the target substance vanadium-tris-acetylacetonate, since the source substance acetylacetonate is a hydrolysis product of vanadium-tris-acetylacetonate.

Executive summary:

In this study (similar to OECD Guideline 413) acetylacetonate was administered to assess the toxic effects by inhalation of the acetylacetonate test item as a vapour to rats (20/sex/group) for 6 hours per day, 5 days per week for 14 weeks at target concentrations of 100, 300 and 650 ppm. An additional 10 males were added to the high dose and control groups for glutaraldehyde perfusion and subsequent transmission electron microscopic examination of sciatic and tibial nerves. Control animals (20/sex) received air only. Chamber concentrations of the test item vapor were analyzed approximately once every 33 min during the 6-hr exposure periods using a Perkin-Elmer Model 3920B gas chromatograph equipped with a flame ionization detector.

Animals were observed daily for signs of toxicity. An Irwin screen for the assessment of neurobehavioural effects was performed prior to the first exposure and monthly thereafter, including just before sacrifice of the recovery animals. Body weight measurements were recorded weekly, once before the first exposure, body weight measurements were also obtained just prior to sacrifice.  Animals of the 4-week recovery period were weighed weekly and immediately before sacrifice. Individual animal food and water consumption was measured for approximately 15 hr in metabolism cages with 10 males and 10 females from each exposure concentration; measurements were made during exposure week 14. Urine was collected while animals were in the metabolism cages. Serum chemistry and hematologic evaluations were performed on blood samples collected from survivors at the end of the 14-week exposure or 4-week recovery periods. Animals were sacrificed, selected organs were weighed and organ/body weight ratios were calculated. A complete gross post-mortem examination was conducted on all animals followed by histologic examination of selected tissues.

The mean analytical exposure concentrations were 101, 307 and 650 ppm for the low, mid and high dose groups, respectively. At 650 ppm, alt females and 10 of 30 males died between the second and sixth weeks of exposure. These animals had acute degenerative changes in the deep cerebellar nuclei, vestibular nuclei and corpora striata, and acute lymphoid degeneration in the thymus. Seven of 15 male survivors of the 650 ppm group had gliosis and malacia in the same brain regions, minimal squamous metaplasia in the nasal mucosa, decreased body and organ weights, lymphocytosis, and minor alterations in serum and urine chemistries. No ultrastructural evidence of peripheral neuropathy was observed. Except for central neuropathy, many of the adverse effects at 650 ppm were less marked in the 4-week recovery animals. No deaths occurred at 307 ppm, but females had slightly decreased body weight gains, and in both sexes there were minor alterations in hematology, serum chemistry, and urinalysis parameters, which were not present in the 4-week recovery animals. Rats exposed to 101 ppm showed no differences from the control rats. Subchronic exposure to 650 ppm of acetylacetonate vapor causes serious adverse biological effects. Under these study conditions, the minimum-effects concentration was 1277.12 mg/m³, and the no-adverse effects concentration was 420 mg/m³.

This result is also valid for the target substance vanadium-tris-acetylacetonate, since the source substance acetylacetonate is a hydrolysis product of vanadium-tris-acetylacetonate.

Reference 2

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

please refer to Read-across statement attached in section 13

Reason / purpose for cross-reference:

read-across source

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

rats: During the first week of the study, red nasal discharge, rapid respiration, and hypoactivity were observed in all 32 mg/m3 rats; rapid respiration was also observed in all rats exposed to 16 mg/m3. Rapid, shallow respiration was most visible during exposure periods but persisted immediately following exposure. From day 8 until the end of the study, rats in the 32 mg/m3 groups became emaciated and had hunched and/or abnormal posture and a rough coat; one of the two surviving males had labored breathing.
mice: Hypoactivity was observed in the 32 mg/m3 groups; one of the affected females also had labored breathing. Some males in the 32 mg/m3 groups had hunched posture, and one was emaciated.

Mortality:

mortality observed, treatment-related

Description (incidence):

rats: Three males exposed to 32 mg/m3 died before the end of the study
mice: All males exposed to 32 mg/m3 died or were killed moribund and one male exposed to 8 mg/m3 died before the end of the study

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

rats: Final mean body weights and body weight gains of males and females exposed to 8 mg/m3 or greater were less than those of the chamber controls.
mice: Final mean body weights and body weight gains of 16 mg/m3 males and 32 mg/m3 females were significantly less than those of the chamber controls; 32 mg/m3 females lost weight during the study. Additionally, final mean body weights of 8 and 16 mg/m3 females were significantly less than those of the chamber controls.

Food efficiency:

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

rats: Urine staining was observed in 32 mg/m3 females

Immunological findings:

no effects observed

Description (incidence and severity):

rats and mice (immunotoxicology study): There were no effects on systemic immunity, evidenced by a normal response to Klebsiella pneumoniae. Other measures of immune function were not considered to be significantly different than those of the chamber controls.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

rats: Relative lung weights of 4 mg/m3 or greater males and 2 mg/m3 or greater females were significantly greater than those of the chamber controls. Other organ weight differences were considered to be related to body weight decreases.
mice: Absolute and relative lung weights of 4 mg/m3 or greater males and all exposed groups of females were significantly greater than those of the chamber controls. In addition, liver weights of 16 mg/m3 males were significantly greater. Other organ weight differences were considered to be related to body weight decreases.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

rats: Gross lesions observed at necropsy were not considered to be exposure related. Complete histopathology was not performed.
mice: Thymus weights were similar to those of the chamber controls in all exposed groups except 32 mg/m3 females. Mediastinal lymph nodes of several males and females exposed to 2 (females only), 4, 8, or 16 mg/m3 were enlarged.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

rats: A localized inflammatory response in the lung was evident in male rats based on increases in cell number, protein, neutrophils, and lysozymes in lavage fluid in all exposed groups. There was also a significant decrease in macrophages in lavage fluids of male rats exposed to 8 or 16 mg/m3.
mice: A localized inflammatory response in the lung was evident based on increases in cell number, protein, lymphocytes, neutrophils, and lysozymes in lavage fluid. There was also a significant decrease in macrophages in lavage fluid.

Histopathological findings: neoplastic:

no effects observed

Other effects:

effects observed, treatment-related

Description (incidence and severity):

rats: Salivation, and diarrhea were observed in 32 mg/m3 females. Ocular or nasal discharge was noted in the 16 mg/m3 groups.

Dose descriptor:

conc. level: body weight deficits > 10%

Remarks:

converted to VAA

Effect level:

61.3 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Remarks on result:

other: rats

Dose descriptor:

conc. level: mortality

Remarks:

converted to VAA

Effect level:

122.5 mg/m³ air

Based on:

test mat.

Sex:

male

Basis for effect level:

mortality

Remarks on result:

other: rats and mice

Critical effects observed:

no

Calculation of effect concentrations of vanadium acetylacetonate:

EC(V) in source substance

Source substance V2O5

MW (V2O5) = 181.88 g/mol

MW (V) = 50.94 g/mol

V in V2O5 = (2*50.94) / 181.88 = 0.56

EC (V) = EC(V2O5) x 0.56 = 16 mg/m3 x 0.56 = 8.96 mg/m3

EC of target substance vanadium acetylacetonate (VAA)

MW V in VAA = 50.94 g/mol

MW VAA = 348.27 g/mol

EC (VAA) in target = EC (V) in source / 50.94 x 348.27

EC (V) in source = 8.96 mg/m3

EC (VAA) in target = 8.96 / 50.94 x 348.27 = 61.3 mg/m3

EC(V) in source substance

Source substance V2O5

MW (V2O5) = 181.88 g/mol

MW (V) = 50.94 g/mol

V in V2O5 = (2*50.94) / 181.88 = 0.56

EC (V) = EC(V2O5) x 0.56 = 32 mg/m3 x 0.56 = 17.92 mg/m3

EC of target substance vanadium acetylacetonate (VAA)

MW V in VAA = 50.94 g/mol

MW VAA = 348.27 g/mol

EC (VAA) in target = EC (V) in source / 50.94 x 348.27

EC (V) in source = 17.92 mg/m3

EC (VAA) in target = 17.92 / 50.94 x 348.27 = 122.5 mg/m3

Conclusions:

In the 16-day studies, mortality occurred in male rats and mice exposed to 32 mg/m3, and body weight deficits greater than 10% were observed in male and female rats exposed to concentrations of 16 mg/m3 or greater and in 32 mg/m3 mice.This corresponds to concentrations of 61.3 and 122.5 mg/m3 of the target substance vanadium-tris-acetylacetonate.

Executive summary:

Rats

Groups of five male and five female rats were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 2, 4, 8, 16, or 32 mg/m3 by inhalation, 6 hours per day, 5 days per week for 16 days. Three males in the 32 mg/m3 group died before the end of the study. Mean body weights of males and females exposed to 8 mg/m3 or greater were less than those of the chamber controls. Clinical findings included rapid respiration and hypoactivity in rats exposed to 16 or 32 mg/m3. Relative lung weights of 4 mg/m3 or greater males and 2 mg/m3 or greater females were significantly greater than those of the chamber controls. Lavage fluid analysis indicated an inflammatory response in the lung that was either directly mediated by vanadium pentoxide or was secondary to lung damage induced by vanadium pentoxide exposure.

Mice

Groups of five male and five female mice were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 2, 4, 8, 16, or 32 mg/m3 by inhalation, 6 hours per day, 5 days per week for 16 days. All males exposed to 32 mg/m3 and one 8 mg/m3 male died or were killed moribund before the end of the study. Mean body weights of 16 mg/m3 males and 8 mg/m3 or greater females were significantly less than those of the chamber controls, and the 32 mg/m3 females lost weight during the study. Absolute and relative lung weights of 4 mg/m3 or greater males and all exposed groups of females and liver weights of 16 mg/m3 males were significantly greater than those of the chamber controls. The mediastinal lymph nodes were enlarged in 4, 8, and 16 mg/m3 males and females, and lymphoid hyperplasia was confirmed histologically. Lavage fluid analysis indicated an inflammatory response in the lung that was either directly mediated by vanadium pentoxide or was secondary to lung damage induced by vanadium pentoxide exposure.

The concentrations of 16 and 32 mg/m3 correspond to doses of 61.3 and 122.5 mg/m3 of the target substance vanadium-tris-acetylacetonate.

Reference 3

Endpoint:

chronic toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

please refer to Read-across statement attached in section 13

Reason / purpose for cross-reference:

read-across source

Clinical signs:

no effects observed

Description (incidence and severity):

rats: No clinical findings related to vanadium pentoxide exposure were observed.
mice: Many animals exposed to vanadium pentoxide were thin, and abnormal breathing was observed in some animals, particularly those exposed to 2 or 4 mg/m3 vanadium pentoxide.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

rats: Survival of exposed males and females was similar to that of the chamber controls.
mice: Survival of males exposed to 4 mg/m3 was significantly less than that of the chamber controls.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

rats: Mean body weights of females exposed to 2 mg/m3 were marginally less than those of the chamber controls throughout the 2-year study; mean body weights of exposed and chamber control males were similar throughout the study
mice: Mean body weights of males exposed to 4 mg/m3 and all exposed groups of females were generally less than those of the chamber controls throughout the study, and mean body weights of males exposed to 2 mg/m3 were less from week 85 to the end of the study.

Food efficiency:

not examined

Ophthalmological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

rat (Tissue burden analysis): Lung weights from exposed female rats increased throughout the study

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant or biologically noteworthy changes in the incidences of neoplasms and nonneoplastic lesions of the lung, larynx, nose, uterus, and kidney were observed (please refer to 'Details on results').

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant or biologically noteworthy changes in the incidences of neoplasms and nonneoplastic lesions of the lung, larynx, nose, uterus, and kidney were observed (please refer to 'Details on results').

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant or biologically noteworthy changes in the incidences of neoplasms and nonneoplastic lesions of the lung, larynx, nose, uterus, and kidney were observed (please refer to 'Details on results').

Details on results:

RATS
Lung: Although there were no statistically significant increases in the incidences of lung neoplasms in rats, the incidences of alveolar/bronchiolar adenoma in 0.5 mg/m3 males and of alveolar/bronchiolar carcinoma and alveolar/bronchiolar adenoma or carcinoma (combined) in 0.5 and 2 mg/m3 males exceeded the historical ranges in controls (all routes) given NTP-2000 diet and in inhalation chamber controls given NIH-07 diet. This response was considered related to exposure to vanadium pentoxide.
Larynx: There were increased incidences of minimal to mild lesions of the larynx in males and females exposed to vanadium pentoxide. The incidences generally increased with increasing exposure concentration and included chronic inflammation of the larynx and degeneration, hyperplasia, and squamous metaplasia of the respiratory epithelium of the epiglottis.
Uterus: The incidences of stromal polyp occurred with a positive trend in female rats (chamber control, 6/50; 0.5 mg/m3, 3/50; 1 mg/m3, 7/50; 2 mg/m3, 13/50)
Kidney: The incidences of nephropathy (37/50, 42/50, 46/49, 47/50; Table A5) were significantly increased in male rats exposed to 1 or 2 mg/m3. Nephropathy is a common lesion in aged rats

MICE
Lung: The incidences of alveolar/bronchiolar carcinoma and alveolar/bronchiolar adenoma or carcinoma (combined) were significantly increased in all groups of exposed male and female mice. The incidences of alveolar/bronchiolar adenoma were significantly increased in males exposed to 2 mg/m3 and in all groups of exposed females.
Larynx: There were significantly increased incidences of minimal squamous metaplasia of the respiratory epithelium of the epiglottis in exposed groups
Nose: There were increased incidences of minimal to mild suppurative inflammation of the nose in males and females exposed to 2 or 4 mg/m3. The majority of the olfactory epithelium covers the turbinates in the distal portion of the nose. There were marginal but significant increases in the incidences of atrophy of this epithelium in females exposed to 1 or 4 mg/m3, and the incidences in exposed males, though not significant, occurred with a positive trend.
Bronchial Lymph Node: There were significant increases in the incidences of hyperplasia of the bronchial lymph node in exposed groups of females, and while not significant, a positive trend in the incidences of this lesion also occurred in males.
Spleen: There was a positive trend in the incidences of hemangiosarcoma of the spleen in male mice (chamber control, 0/50; 1 mg/m3, 0/50; 2 mg/m3, 0/50; 4 mg/m3, 3/50.
Other Organs: There was a significant decrease in the incidence of harderian gland adenoma in male mice exposed to 4 mg/m3; however, the incidence of harderian gland adenoma or carcinoma (combined) in this group was not statistically significant. Negative trends in the incidences of hepatocellular adenoma and hepatocellular adenoma or carcinoma (combined) occurred in males.

Dose descriptor:

conc. level: mortality

Remarks:

mice

Effect level:

15.3 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

mortality

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: body weight deficits

Remarks:

mice

Effect level:

3.8 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

body weight and weight gain

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: abnormal breathing

Remarks:

mice

Effect level:

7.7 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: body weight deficits

Remarks:

rats

Effect level:

7.7 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

body weight and weight gain

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: alveolar/bronchiolar adenomaalveolar/bronchiolar adenomas

Remarks:

rats

Effect level:

1.9 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: alveolar/bronchiolar adenomas

Remarks:

mice

Effect level:

7.7 mg/m³ air

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: mice

Effect level:

3.8 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: converted to VAA

Critical effects observed:

yes

Lowest effective dose / conc.:

1.9 mg/m³ air

System:

respiratory system: lower respiratory tract

Organ:

alveoli

bronchi

bronchioles

lungs

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Tissue Burden Analyses

Tissue burden analyses were performed on female rats exposed to 0.5, 1, or 2 mg/m3 on days 1, 5, 12, 26, 54, 173, 360, and 540. Lung weights from exposed female rats increased throughout the study.

Various tests used to determine if lung burdens were proportional to exposure concentration gave contradictory results. Simple visual inspection of the lung burden data indicates that lung burdens increased roughly in proportion to exposure concentration. Lung burdens normalized to exposure concentration would be expected to remain constant across all exposure concentrations if the toxicokinetics were linear. Although proportionality may not have been evident when examined at several individual time points, departures from proportional behavior were small. However, when lung burden data were integrated over all time points, they did appear to be approximately proportional to exposure concentration.

Though deposition patterns were similar between rats and mice, the maximum lung burdens occurred much later in rats (day 173) than in mice (days 26 to 54). The lung burdens appeared to reach steady state at the lowest exposure concentrations in rats (0.5 mg/m3) and mice (1 mg/m3). A decline in lung burdens was observed in both species. It is possible that the decreased deposition rates in rats exposed to 1 mg/m3 or greater and mice exposed to 2 mg/m3 or greater were due to a change in pulmonary function brought about by vanadium pentoxide-induced alterations in the airways and alveoli of the lung as was observed in the 3-month rat studies. The retention of vanadium in the lungs at 18 months was lower in mice (2% to 3%) than in rats (13% to 15%) at comparable exposure concentrations.

From the lung burden studies, the total lung “dose” was estimated for each exposure concentration to aid in interpretation of lung pathology in exposed rats and mice. The total lung doses for rats exposed to 0.5, 1, or 2 mg/m3 were estimated to be 130, 175, and 308 μg vanadium, respectively. The total lung doses for mice exposed to 1, 2, or 4 mg/m3 were 153, 162, and 225 μg vanadium, respectively. There was little difference in the total lung dose for mice, especially between the 1 and 2 mg/m3 groups.

Conclusions:

Under the conditions of this 2-year inhalation study, there was some evidence of carcinogenic activity* of vanadium pentoxide in male F344/N rats and equivocal evidence of carcinogenic activity* of vanadium pentoxide in female F344/N rats based on the occurrence of alveolar/bronchiolar neoplasms. There was clear evidence of carcinogenic activity* of vanadium pentoxide in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms.
Exposure to vanadium pentoxide caused a spectrum of nonneoplastic lesions in the respiratory tract (nose, larynx, and lung) including alveolar and bronchiolar epithelium hyperplasia, inflammation, fibrosis, and alveolar histiocytosis of the lung in male and female rats and mice and an unusual squamous metaplasia of the lung in male and female rats. Hyperplasia of the bronchial lymph node occurred in female mice.

(*) -Clear evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a dose-related (i) increase of malignant neoplasms, (ii) increase of a combination of malignant and benign neoplasms, or (iii) marked increase of benign neoplasms if there is an indication from this or other studies of the ability of such tumors to progress to malignancy.
-Some evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a chemical-related increased incidence of neoplasms (malignant, benign, or combined) in which the strength of the response is less than that required for clear evidence.
-Equivocal evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a marginal increase of neoplasms that may be chemical related.
-No evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing no chemical-related increases in malignant or benign neoplasms.
-Inadequate study of carcinogenic activity is demonstrated by studies that, because of major qualitative or quantitative limitations, cannot be interpreted as valid for showing either the presence or absence of carcinogenic activity.

Executive summary:

rats

Groups of 50 male and 50 female rats were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 0.5, 1, or 2 mg/m3 by inhalation, 6 hours per day, 5 days per week for 104 weeks. Survival and body weights of males and females were generally similar to those of the chamber controls. Mean body weights of females exposed to 2 mg/m3 were less than those of the chamber controls throughout the study. Alveolar/bronchiolar neoplasms were present in exposed groups of male rats, and the incidences often exceeded the historical control ranges. Alveolar/bronchiolar adenomas were present in 0.5 and 1 mg/m3 females; one 2 mg/m3 female also had an alveolar/bronchiolar carcinoma. The incidence of alveolar/bronchiolar adenoma in the 0.5 mg/m3 group was at the upper end of the historical control ranges. Nonneoplastic lesions related to vanadium pentoxide exposure occurred in the respiratory system (lung, larynx, and nose) of male and female rats, and the severities of these lesions generally increased with increasing exposure concentration.

0.5, 1 and 2 mg/m3 vanadium pentoxide correspond to 1.9, 3.8 and 7.7 mg/m3 vanadium-tris-acetylacetonate.

mice

Groups of 50 male and 50 female mice were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 1, 2, or 4 mg/m3 by inhalation, 6 hours per day, 5 days per week for 104 weeks. Survival of 4 mg/m3 males was significantly less than that of the chamber controls. Mean body weights of 4 mg/m3 males and all exposed groups of females were generally less than those of the chamber controls throughout the study, and those of males exposed to 2 mg/m3 were less from week 85 to the end of the study. Many mice exposed to vanadium pentoxide were thin, and abnormal breathing was observed in some mice, particularly those exposed to 2 or 4 mg/m3. The incidences of alveolar/bronchiolar neoplasms were significantly increased in all groups of exposed males and females. Nonneoplastic lesions related to vanadium pentoxide exposure occurred in the respiratory system (lung, larynx, and nose) of male and female mice, and the severities of these lesions generally increased with increasing exposure concentration. Bronchial lymph node hyperplasia was present in many exposed females.

1, 2 and 4 mg/m3 vanadium pentoxide correspond to 3.8, 7.7 and 15.3 mg/m3 vanadium-tris-acetylacetonate.

For details on the calculations, please refer to 'Overall Remarks'

Carcinogenicity

Under the conditions of this 2-year inhalation study, there was some evidence of carcinogenic activity* of vanadium pentoxide in male F344/N rats and equivocal evidence of carcinogenic activity* of vanadium pentoxide in female F344/N rats based on the occurrence of alveolar/bronchiolar neoplasms. There was clear evidence of carcinogenic activity* of vanadium pentoxide in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms.

Exposure to vanadium pentoxide caused a spectrum of nonneoplastic lesions in the respiratory tract (nose, larynx, and lung) including alveolar and bronchiolar epithelium hyperplasia, inflammation, fibrosis, and alveolar histiocytosis of the lung in male and female rats and mice and an unusual squamous metaplasia of the lung in male and female rats. Hyperplasia of the bronchial lymph node occurred in female mice.

(*) -Clear evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a dose-related (i) increase of malignant neoplasms, (ii) increase of a combination of malignant and benign neoplasms, or (iii) marked increase of benign neoplasms if there is an indication from this or other studies of the ability of such tumors to progress to malignancy.

-Some evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a chemical-related increased incidence of neoplasms (malignant, benign, or combined) in which the strength of the response is less than that required for clear evidence.

-Equivocal evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a marginal increase of neoplasms that may be chemical related.

-No evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing no chemical-related increases in malignant or benign neoplasms.

-Inadequate study of carcinogenic activity is demonstrated by studies that, because of major qualitative or quantitative limitations, cannot be interpreted as valid for showing either the presence or absence of carcinogenic activity.

Reference 4

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

please refer to Read-across statement attached in section 13

Reason / purpose for cross-reference:

read-across source

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

rats: Abnormal breathing, thinness, lethargy, abnormal posture, and ruffled fur were observed in rats exposed to 16 mg/m3. Abnormal breathing, marked by shallow, rapid respiration, was first observed during and immediately following exposure periods; this was observed in all 16 mg/m3 rats by week 2 and in all 8 mg/m3 rats by week 4. By week 9, the abnormal breathing was also observed in 16 mg/m3 rats during nonexposure periods. Some rats in the 16 mg/m3 groups had diarrhea and nasal/eye discharge. Abnormal posture was observed in two males exposed to 8 mg/m3, and one of these rats was thin with ruffled fur and nasal/eye discharge.

Mortality:

mortality observed, treatment-related

Description (incidence):

rats: Seven males and three females exposed to 16 mg/m3 died during the study.
mice: One male exposed to 16 mg/m3 died before the end of the study. The mouse that died early appeared thin. There were no other clinical findings related to vanadium pentoxide exposure.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

rats: Final mean body weights and body weight gains of males exposed to 4 mg/m3 or greater and of females exposed to 16 mg/m3 were significantly less than those of the chamber controls.
mice: Final mean body weights and body weight gains of 8 and 16 mg/m3 males and of 4 mg/m3 or greater females were significantly less than those of the chamber controls.

Food efficiency:

not specified

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

rats: The hematology results indicated that exposure of rats to vanadium pentoxide affected the circulating red cell mass. In general, the erythrocyte counts reflected similar and proportional, but not significant, decreases. There were exposure concentration-related decreases in the mean cell volumes and mean cell hemoglobin values on day 23, which are consistent with a developing erythrocyte microcytosis. The mean cell volumes and/or mean cell hemoglobin values were decreased in 2 mg/m3 or greater males and 4 mg/m3 or greater females, suggesting that the circulating erythrocytes were smaller than expected. At week 13, the erythron decrease had disappeared and was replaced by an erythrocytosis, evidenced by substantial increases in hematocrit values, hemoglobin concentrations, and erythrocyte counts in 16 mg/m3 males and females. The erythrocytosis was accompanied by increased reticulocyte and/or nucleated erythrocyte counts, suggesting that an increased production of erythrocytes contributed to the erythrocytosis.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

rats: Serum alanine aminotransferase activities were increased. Stress-related corticosteroid-induced increases in liver alanine aminotransferase activities may, in part, help explain this . At all time points, there were generally exposure concentration-related decreases in serum alkaline phosphatase activities and total protein and albumin concentrations in males and females. At week 13, urea nitrogen concentrations were increased in 16 mg/m3 males and females, suggesting a possible effect on renal clearance. However, creatinine concentrations, another marker of renal clearance, were minimally decreased on day 23 in 8 mg/m3 males and at week 13 in 16 mg/m3 males and females; these decreases would be consistent with the decreased body weights observed in these groups. Since alkaline phosphatase activity and total protein, albumin, and urea nitrogen concentrations can be affected by altered nutritional status, the changes in these variables may have been related secondarily to body weight decreases and altered food intake. Significant increases and decreases in bile acid concentrations and creatine kinase activities in various exposure groups at various time points were not considered to be toxicologically relevant.

Urinalysis findings:

effects observed, non-treatment-related

Description (incidence and severity):

rats: After 12 (females) or 13 (males) weeks of exposure, the baseline (water-replete) overnight urine collection demonstrated decreased urine volumes and increased urine specific gravities in the 8 mg/m3 male and 16 mg/m3 female groups, suggesting these animals were able to concentrate their urine; the 16 mg/m3 male group was not tested. These findings also suggest that these exposure groups may have been in a partially dehydrated state prior to the water deprivation studies. For baseline and water deprivation test samples, microscopic evaluation of the urine demonstrated slight increases in formed elements in 8 mg/m3 males (baseline: casts, epithelial cells, erythrocytes, and leukocytes; water-deprived: casts) and 16 mg/m3 females (baseline and water deprived: leukocytes) (data not presented). While changes in formed urine elements can be indicative of various renal effects, the alterations in this study were not excessive and possibly reflected the hydration status of the animals; they were not considered to be toxicologically relevant.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

rats: Absolute and relative lung weights of 4 mg/m3 or greater males and females were significantly greater than those of the chamber controls; in addition, the relative lung weights of 2 mg/m3 males were significantly greater than those of the chamber controls.
mice: Absolute and relative lung weights of males and females exposed to 4 mg/m3 or greater were significantly greater than those of the chamber controls. The absolute lung weight was also significantly increased in males exposed to 2 mg/m3.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

rats: The carcasses of males and females exposed to 16 mg/m3 were very thin, and the spleens and thymuses appeared disproportionately small. Lungs of 4 mg/m3 or greater males and 8 and 16 mg/m3 females varied from red to pale or mottled.
mice: Gross findings were observed in males and females exposed to 8 or 16 mg/m3 and included lungs that were pale or contained white or red (females) foci; the lungs of males in these groups were sometimes gray or mottled.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

rats: There were significant increases in the incidences of epithelial hyperplasia of the lung in males and females exposed to 2 mg/m3 or greater. The incidences of inflammation or fibrosis were significantly increased in males exposed to 2 mg/m3 or greater and females exposed to 4 mg/m3 or greater. The incidences of hyperplasia and metaplasia of the nasal respiratory epithelium were significantly increased in males exposed to 8 or 16 mg/m3 and in females exposed to 4 mg/m3 or greater. There were significantly increased incidences of inflammation of the nose in males and females exposed to 16 mg/m3.
mice: The incidences of inflammation of the lung were increased in mice exposed to 2 mg/m3 or greater. Mice exposed to 2 mg/m3 or greater had epithelial hyperplasia of the lung. The severities of these lesions generally increased with increasing exposure concentration. Inflammation was characterized by multiple foci of a mixed cellular infiltrate oriented around blood vessels and bronchioles. The infiltrate was composed primarily of macrophages with abundant cytoplasm and fewer lymphocytes and neutrophils. The infiltrate extended into the surrounding perivascular interstitium and often filled adjacent alveoli. Hyperplasia involved alveolar and, to a lesser extent, bronchiolar epithelium. This change involved the distal airways and associated alveolar ducts and alveoli. Normally flattened epithelium was replaced with larger cuboidal cells.

Other effects:

effects observed, treatment-related

Description (incidence and severity):

rats: Vanadium pentoxide exposure did not affect reproductive endpoints in males, but it did increase estrous cycle length in females exposed to 8 mg/m3 and reduced the number of cycling females in the 16 mg/m3 group.
mice: The epididymal spermatozoal motility of males exposed to 8 or 16 mg/m3 was significantly decreased. No significant differences were noted in estrous cycle parameters between exposed and chamber control females.

Dose descriptor:

NOAEL

Remarks:

rats and mice

Effect level:

3.8 mg/m³ air

Based on:

test mat.

Remarks:

converted to VAA

Sex:

male/female

Basis for effect level:

other: pulmonary effect

Critical effects observed:

yes

Lowest effective dose / conc.:

7.7 mg/m³ air

System:

respiratory system: upper respiratory tract

Organ:

alveoli

bronchi

bronchioles

lungs

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Critical effects observed:

yes

Lowest effective dose / conc.:

15.3 mg/m³ air

System:

respiratory system: upper respiratory tract

Organ:

other: nose (respiratory epithelium covering the ventral portion of the nasal septum, the vomeronasal organ, and, to a lesser extent, the ventral lateral walls of the anterior portion of the nasal cavity)

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Cardiopulmonary Physiology Studies

Decreases in heart rate and in diastolic, systolic, and mean blood pressure were observed in male and female rats exposed to 16 mg/m3. It is unlikely that this response was the result of a direct cardiotoxic action of vanadium pentoxide, rather, it was considered to be a reflection of the poor condition of the animals coupled with an effect from anesthesia.

Significant exposure-related changes in pulmonary function were observed in male and female rats exposed to 4, 8, or 16 mg/m3. Only slight differences were observed between males and females, and the differences were not considered to be biologically significant. These results indicate that a more restrictive lesion was present in groups exposed to 4 mg/m3 or greater, evidenced by reduced lung compliance, changes in breathing measurements, impaired capacity to diffuse carbon monoxide, reduced static and dynamic lung volumes, and exaggerated flows. Exposure concentration-related decreases in chord, peak, and dynamic compliance were consistent with reduced lung elasticity. There was also an increase in respiratory rate and a decrease in tidal volume; these alterations are known to increase breathing efficiency in response to a restrictive disease. This breathing pattern preferentially ventilates airway dead space and results in increased minute volume to maintain adequate blood gas. Also characteristic of restrictive disease were reduced carbon monoxide diffusing capacity, which signifies obstructed airways and changes in membrane composition (thickened interstitium). The decrease in static lung volume (total lung capacity and vital capacity) and exaggerated flows, as described by flow volume curves corrected for lung volume, also were suggestive of restrictive disease.

Pulmonary function changes indicate an obstructive disease in the 16 mg/m3 groups, evidenced by changes in breathing mechanics, static lung volumes, and forced expiratory maneuvers. Expiratory resistance, an indicator of bronchoconstriction, and end expiratory and residual volume were increased, while dynamic lung volume was decreased. These changes suggest closure of distal airways due to extensive pathology, resulting in air being trapped in the alveoli and reduced flow during forced expiratory maneuvers. Lung pathology in rats exposed to 16 mg/m3 was not drastically different than that observed in rats exposed to 8 mg/m3. Thus, it is not clear whether pulmonary function results indicate an obstructive disease or merely reflect the deteriorating condition of the 16 mg/m3 rats.

Together, the pulmonary function changes indicate that a restrictive disease was present in male and female rats exposed to 4 mg/m3 or greater, while an obstructive lung disease may have been present only in the 16 mg/m3 groups.

The pulmonary lavage data indicate an inflammatory response in the lungs of exposed rats. In general, there were no differences between males and females. Exposure concentration-related increases were observed in the total numbers of cells, lymphocytes, neutrophils, and protein recovered in pulmonary lavage fluid from rats exposed to vanadium pentoxide at concentrations up to 8 mg/m3. The percentages of macrophages in lavage fluid were similar between exposed and chamber control rats. However, in female rats exposed to 8 mg/m3 there was a decrease in the numbers of macrophages with concomitant increases in the numbers of neutrophils and lymphocytes. These endpoints also were affected in the 16 mg/m3 group, but to a lesser extent, which is most likely due to the overt toxicity of vanadium pentoxide evidenced by decreased body weights and severe bronchoconstriction and airway obstruction.

Conclusions:

the 16 mg/m3 concentration was lethal to several rats and one male mouse; body weights were severely reduced in rats exposed to 16 mg/m3. The respiratory tract was clearly the primary site of toxicity in rats and mice exposed to vanadium pentoxide, with rats being somewhat more severely affected than mice. The respiratory effects were more intense with increased exposure time, as indicated by increased lung weights and a greater spectrum and increased severity of proliferative and inflammatory lesions in the lungs of most exposed rats and mice in the 3-month studies. Alveolar/bronchiolar epithelial hyperplasia was present in all mice exposed to 8 or 16 mg/m3, but occurred with greater severity and was present in all rats exposed to 2 mg/m3 or greater. The severities of pulmonary inflammation were similar between rats and mice, but the incidences of this lesion were significantly increased at lower concentrations in rats. Minimal to moderate fibrosis of the lung occurred in rats exposed to 2 mg/m3 or greater. The no-observed-adverse-effect level for lungs was 1 mg/m3 in rats and was not determined in mice. Taken together, hyperplastic and inflammatory lesions, the presence of exudate in the bronchioles, and lavage fluid analysis supported conclusions from the pulmonary function tests that indicated restrictive lung disease in rats exposed to 4 mg/m3 or greater.

The NOAEL of 1 mg/m3 corresponds to a concentration of 3.8 mg/m3 when converted to the target substance vanadium-tris-acetylacetonate. The effect concentrations 2 and 4 mg/m3 correspond to 7.7 and 15.3 mg/m3 vanadium-tris-acetylacetonate. For details about the calculations, please refer to "Overall Remarks".

The NOAEL of 1 mg/m3 corresponds to a concentration of 3.8 mg/m3 when converted to the target substance vanadium-tris-acetylacetonate. The effect concentrations 2 and 4 mg/m3 correspond to 7.7 and 15.3 mg/m3 vanadium-tris-acetylacetonate. For details about the calculations, please refer to "Overall Remarks".

Executive summary:

Rats

Groups of 10 male and 10 female rats were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 1, 2, 4, 8, or 16 mg/m3 by inhalation, 6 hours per day, 5 days per week for 3 months. Seven males and three females exposed to 16 mg/m3 died during the study. Mean body weights were significantly less in males exposed to 4 mg/m3 or greater and in females exposed to 16 mg/m3. Abnormal breathing, thinness, lethargy, abnormal posture, and ruffled fur were observed in rats exposed to 16 mg/m3.

Hematology results indicated that exposure of rats to vanadium pentoxide induced a microcytic erythrocytosis in males and females. Absolute and relative lung weights were significantly greater for 4 mg/m3 or greater males and females than for the chamber controls as were the relative lung weights of 2 mg/m3 males. The estrous cycle of females exposed to 8 mg/m3 was significantly longer than that of the chamber control group, and the number of cycling females in the 16 mg/m3 group was reduced. The incidences of several nonneoplastic lesions of the lung and nose were significantly increased in males and females exposed to 2 mg/m3 or greater. Data from pulmonary function analyses indicated that a restrictive lung disease was present in male and female rats exposed to 4 mg/m3 or greater, while an obstructive lung disease was present only in the 16 mg/m3 groups.

Mice

Groups of 10 male and 10 female mice were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 1, 2, 4, 8, or 16 mg/m3 by inhalation, 6 hours per day, 5 days per week for 3 months. One male exposed to 16 mg/m3 died before the end of the study. Mean body weights of 8 and 16 mg/m3 males and 4 mg/m3 or greater females were significantly less than those of the chamber controls. Absolute and relative lung weights of males and females exposed to 4 mg/m3 or greater were significantly greater than those of the chamber controls. The epididymal spermatozoal motility of males exposed to 8 or 16 mg/m3 was significantly decreased. Some mice exposed to 2 or 4 mg/m3 had inflammation of the lung, and all mice exposed to 8 or 16 mg/m3 had inflammation and epithelial hyperplasia of the lung.

The NOAEL of 1 mg/m3 corresponds to a concentration of 3.8 mg/m3 when converted to the target substance vanadium-tris-acetylacetonate. The effect concentrations 2 and 4 mg/m3 correspond to 7.7 and 15.3 mg/m3 vanadium-tris-acetylacetonate. For details about the calculations, please refer to "Overall Remarks".

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

1.9 mg/m³

Study duration:

chronic

Species:

rat

System:

respiratory system: lower respiratory tract

Organ:

alveoli

bronchi

bronchioles

lungs

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

chronic toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

please refer to Read-across statement attached in section 13

Reason / purpose for cross-reference:

read-across source

Clinical signs:

no effects observed

Description (incidence and severity):

rats: No clinical findings related to vanadium pentoxide exposure were observed.
mice: Many animals exposed to vanadium pentoxide were thin, and abnormal breathing was observed in some animals, particularly those exposed to 2 or 4 mg/m3 vanadium pentoxide.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

rats: Survival of exposed males and females was similar to that of the chamber controls.
mice: Survival of males exposed to 4 mg/m3 was significantly less than that of the chamber controls.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

rats: Mean body weights of females exposed to 2 mg/m3 were marginally less than those of the chamber controls throughout the 2-year study; mean body weights of exposed and chamber control males were similar throughout the study
mice: Mean body weights of males exposed to 4 mg/m3 and all exposed groups of females were generally less than those of the chamber controls throughout the study, and mean body weights of males exposed to 2 mg/m3 were less from week 85 to the end of the study.

Food efficiency:

not examined

Ophthalmological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

rat (Tissue burden analysis): Lung weights from exposed female rats increased throughout the study

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant or biologically noteworthy changes in the incidences of neoplasms and nonneoplastic lesions of the lung, larynx, nose, uterus, and kidney were observed (please refer to 'Details on results').

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant or biologically noteworthy changes in the incidences of neoplasms and nonneoplastic lesions of the lung, larynx, nose, uterus, and kidney were observed (please refer to 'Details on results').

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant or biologically noteworthy changes in the incidences of neoplasms and nonneoplastic lesions of the lung, larynx, nose, uterus, and kidney were observed (please refer to 'Details on results').

Details on results:

RATS
Lung: Although there were no statistically significant increases in the incidences of lung neoplasms in rats, the incidences of alveolar/bronchiolar adenoma in 0.5 mg/m3 males and of alveolar/bronchiolar carcinoma and alveolar/bronchiolar adenoma or carcinoma (combined) in 0.5 and 2 mg/m3 males exceeded the historical ranges in controls (all routes) given NTP-2000 diet and in inhalation chamber controls given NIH-07 diet. This response was considered related to exposure to vanadium pentoxide.
Larynx: There were increased incidences of minimal to mild lesions of the larynx in males and females exposed to vanadium pentoxide. The incidences generally increased with increasing exposure concentration and included chronic inflammation of the larynx and degeneration, hyperplasia, and squamous metaplasia of the respiratory epithelium of the epiglottis.
Uterus: The incidences of stromal polyp occurred with a positive trend in female rats (chamber control, 6/50; 0.5 mg/m3, 3/50; 1 mg/m3, 7/50; 2 mg/m3, 13/50)
Kidney: The incidences of nephropathy (37/50, 42/50, 46/49, 47/50; Table A5) were significantly increased in male rats exposed to 1 or 2 mg/m3. Nephropathy is a common lesion in aged rats

MICE
Lung: The incidences of alveolar/bronchiolar carcinoma and alveolar/bronchiolar adenoma or carcinoma (combined) were significantly increased in all groups of exposed male and female mice. The incidences of alveolar/bronchiolar adenoma were significantly increased in males exposed to 2 mg/m3 and in all groups of exposed females.
Larynx: There were significantly increased incidences of minimal squamous metaplasia of the respiratory epithelium of the epiglottis in exposed groups
Nose: There were increased incidences of minimal to mild suppurative inflammation of the nose in males and females exposed to 2 or 4 mg/m3. The majority of the olfactory epithelium covers the turbinates in the distal portion of the nose. There were marginal but significant increases in the incidences of atrophy of this epithelium in females exposed to 1 or 4 mg/m3, and the incidences in exposed males, though not significant, occurred with a positive trend.
Bronchial Lymph Node: There were significant increases in the incidences of hyperplasia of the bronchial lymph node in exposed groups of females, and while not significant, a positive trend in the incidences of this lesion also occurred in males.
Spleen: There was a positive trend in the incidences of hemangiosarcoma of the spleen in male mice (chamber control, 0/50; 1 mg/m3, 0/50; 2 mg/m3, 0/50; 4 mg/m3, 3/50.
Other Organs: There was a significant decrease in the incidence of harderian gland adenoma in male mice exposed to 4 mg/m3; however, the incidence of harderian gland adenoma or carcinoma (combined) in this group was not statistically significant. Negative trends in the incidences of hepatocellular adenoma and hepatocellular adenoma or carcinoma (combined) occurred in males.

Dose descriptor:

conc. level: mortality

Remarks:

mice

Effect level:

15.3 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

mortality

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: body weight deficits

Remarks:

mice

Effect level:

3.8 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

body weight and weight gain

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: abnormal breathing

Remarks:

mice

Effect level:

7.7 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: body weight deficits

Remarks:

rats

Effect level:

7.7 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

body weight and weight gain

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: alveolar/bronchiolar adenomaalveolar/bronchiolar adenomas

Remarks:

rats

Effect level:

1.9 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: alveolar/bronchiolar adenomas

Remarks:

mice

Effect level:

7.7 mg/m³ air

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: converted to VAA

Dose descriptor:

conc. level: mice

Effect level:

3.8 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: converted to VAA

Critical effects observed:

yes

Lowest effective dose / conc.:

1.9 mg/m³ air

System:

respiratory system: lower respiratory tract

Organ:

alveoli

bronchi

bronchioles

lungs

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

yes

Tissue Burden Analyses

Tissue burden analyses were performed on female rats exposed to 0.5, 1, or 2 mg/m3 on days 1, 5, 12, 26, 54, 173, 360, and 540. Lung weights from exposed female rats increased throughout the study.

Various tests used to determine if lung burdens were proportional to exposure concentration gave contradictory results. Simple visual inspection of the lung burden data indicates that lung burdens increased roughly in proportion to exposure concentration. Lung burdens normalized to exposure concentration would be expected to remain constant across all exposure concentrations if the toxicokinetics were linear. Although proportionality may not have been evident when examined at several individual time points, departures from proportional behavior were small. However, when lung burden data were integrated over all time points, they did appear to be approximately proportional to exposure concentration.

Though deposition patterns were similar between rats and mice, the maximum lung burdens occurred much later in rats (day 173) than in mice (days 26 to 54). The lung burdens appeared to reach steady state at the lowest exposure concentrations in rats (0.5 mg/m3) and mice (1 mg/m3). A decline in lung burdens was observed in both species. It is possible that the decreased deposition rates in rats exposed to 1 mg/m3 or greater and mice exposed to 2 mg/m3 or greater were due to a change in pulmonary function brought about by vanadium pentoxide-induced alterations in the airways and alveoli of the lung as was observed in the 3-month rat studies. The retention of vanadium in the lungs at 18 months was lower in mice (2% to 3%) than in rats (13% to 15%) at comparable exposure concentrations.

From the lung burden studies, the total lung “dose” was estimated for each exposure concentration to aid in interpretation of lung pathology in exposed rats and mice. The total lung doses for rats exposed to 0.5, 1, or 2 mg/m3 were estimated to be 130, 175, and 308 μg vanadium, respectively. The total lung doses for mice exposed to 1, 2, or 4 mg/m3 were 153, 162, and 225 μg vanadium, respectively. There was little difference in the total lung dose for mice, especially between the 1 and 2 mg/m3 groups.

Conclusions:

Under the conditions of this 2-year inhalation study, there was some evidence of carcinogenic activity* of vanadium pentoxide in male F344/N rats and equivocal evidence of carcinogenic activity* of vanadium pentoxide in female F344/N rats based on the occurrence of alveolar/bronchiolar neoplasms. There was clear evidence of carcinogenic activity* of vanadium pentoxide in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms.
Exposure to vanadium pentoxide caused a spectrum of nonneoplastic lesions in the respiratory tract (nose, larynx, and lung) including alveolar and bronchiolar epithelium hyperplasia, inflammation, fibrosis, and alveolar histiocytosis of the lung in male and female rats and mice and an unusual squamous metaplasia of the lung in male and female rats. Hyperplasia of the bronchial lymph node occurred in female mice.

(*) -Clear evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a dose-related (i) increase of malignant neoplasms, (ii) increase of a combination of malignant and benign neoplasms, or (iii) marked increase of benign neoplasms if there is an indication from this or other studies of the ability of such tumors to progress to malignancy.
-Some evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a chemical-related increased incidence of neoplasms (malignant, benign, or combined) in which the strength of the response is less than that required for clear evidence.
-Equivocal evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a marginal increase of neoplasms that may be chemical related.
-No evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing no chemical-related increases in malignant or benign neoplasms.
-Inadequate study of carcinogenic activity is demonstrated by studies that, because of major qualitative or quantitative limitations, cannot be interpreted as valid for showing either the presence or absence of carcinogenic activity.

Executive summary:

rats

Groups of 50 male and 50 female rats were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 0.5, 1, or 2 mg/m3 by inhalation, 6 hours per day, 5 days per week for 104 weeks. Survival and body weights of males and females were generally similar to those of the chamber controls. Mean body weights of females exposed to 2 mg/m3 were less than those of the chamber controls throughout the study. Alveolar/bronchiolar neoplasms were present in exposed groups of male rats, and the incidences often exceeded the historical control ranges. Alveolar/bronchiolar adenomas were present in 0.5 and 1 mg/m3 females; one 2 mg/m3 female also had an alveolar/bronchiolar carcinoma. The incidence of alveolar/bronchiolar adenoma in the 0.5 mg/m3 group was at the upper end of the historical control ranges. Nonneoplastic lesions related to vanadium pentoxide exposure occurred in the respiratory system (lung, larynx, and nose) of male and female rats, and the severities of these lesions generally increased with increasing exposure concentration.

0.5, 1 and 2 mg/m3 vanadium pentoxide correspond to 1.9, 3.8 and 7.7 mg/m3 vanadium-tris-acetylacetonate.

mice

Groups of 50 male and 50 female mice were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 1, 2, or 4 mg/m3 by inhalation, 6 hours per day, 5 days per week for 104 weeks. Survival of 4 mg/m3 males was significantly less than that of the chamber controls. Mean body weights of 4 mg/m3 males and all exposed groups of females were generally less than those of the chamber controls throughout the study, and those of males exposed to 2 mg/m3 were less from week 85 to the end of the study. Many mice exposed to vanadium pentoxide were thin, and abnormal breathing was observed in some mice, particularly those exposed to 2 or 4 mg/m3. The incidences of alveolar/bronchiolar neoplasms were significantly increased in all groups of exposed males and females. Nonneoplastic lesions related to vanadium pentoxide exposure occurred in the respiratory system (lung, larynx, and nose) of male and female mice, and the severities of these lesions generally increased with increasing exposure concentration. Bronchial lymph node hyperplasia was present in many exposed females.

1, 2 and 4 mg/m3 vanadium pentoxide correspond to 3.8, 7.7 and 15.3 mg/m3 vanadium-tris-acetylacetonate.

For details on the calculations, please refer to 'Overall Remarks'

Carcinogenicity

Under the conditions of this 2-year inhalation study, there was some evidence of carcinogenic activity* of vanadium pentoxide in male F344/N rats and equivocal evidence of carcinogenic activity* of vanadium pentoxide in female F344/N rats based on the occurrence of alveolar/bronchiolar neoplasms. There was clear evidence of carcinogenic activity* of vanadium pentoxide in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms.

Exposure to vanadium pentoxide caused a spectrum of nonneoplastic lesions in the respiratory tract (nose, larynx, and lung) including alveolar and bronchiolar epithelium hyperplasia, inflammation, fibrosis, and alveolar histiocytosis of the lung in male and female rats and mice and an unusual squamous metaplasia of the lung in male and female rats. Hyperplasia of the bronchial lymph node occurred in female mice.

(*) -Clear evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a dose-related (i) increase of malignant neoplasms, (ii) increase of a combination of malignant and benign neoplasms, or (iii) marked increase of benign neoplasms if there is an indication from this or other studies of the ability of such tumors to progress to malignancy.

-Some evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a chemical-related increased incidence of neoplasms (malignant, benign, or combined) in which the strength of the response is less than that required for clear evidence.

-Equivocal evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a marginal increase of neoplasms that may be chemical related.

-No evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing no chemical-related increases in malignant or benign neoplasms.

-Inadequate study of carcinogenic activity is demonstrated by studies that, because of major qualitative or quantitative limitations, cannot be interpreted as valid for showing either the presence or absence of carcinogenic activity.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

1.9 mg/m³

Study duration:

chronic

Species:

rat

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

2,4 -pentanedione

sub-chronic study (Dodd, 1986)

Acetylacetonate was administered to assess the toxic effects by inhalation of the acetylacetonate test item as a vapour to rats (20/sex/group) for 6 hours per day, 5 days per week for 14 weeks at target concentrations of 100, 300 and 650 ppm. An additional 10 males were added to the high dose and control groups for glutaraldehyde perfusion and subsequent transmission electron microscopic examination of sciatic and tibial nerves. Control animals (20/sex) received air only. Chamber concentrations of the test item vapour were analyzed approximately once every 33 min during the 6-hr exposure periods using a Perkin-Elmer Model 3920B gas chromatograph equipped with a flame ionization detector.

Animals were observed daily for signs of toxicity. An Irwin screen for the assessment of neurobehavioural effects was performed prior to the first exposure and monthly thereafter, including just before sacrifice of the recovery animals. Body weight measurements were recorded weekly, once before the first exposure, body weight measurements were also obtained just prior to sacrifice. Animals of the 4-week recovery period were weighed weekly and immediately before sacrifice. Individual animal food and water consumption was measured for approximately 15 hr in metabolism cages with 10 males and 10 females from each exposure concentration; measurements were made during exposure week 14. Urine was collected while animals were in the metabolism cages. Serum chemistry and hematologic evaluations were performed on blood samples collected from survivors at the end of the 14-week exposure or 4-week recovery periods. Animals were sacrificed, selected organs were weighed and organ/body weight ratios were calculated. A complete gross post-mortem examination was conducted on all animals followed by histologic examination of selected tissues.

The mean analytical exposure concentrations were 101, 307 and 650 ppm for the low, mid and high dose groups, respectively. At 650 ppm, all females and 10 of 30 males died between the second and sixth weeks of exposure. These animals had acute degenerative changes in the deep cerebellar nuclei, vestibular nuclei and corpora striata, and acute lymphoid degeneration in the thymus. Seven of 15 male survivors of the 650 ppm group had gliosis and malacia in the same brain regions, minimal squamous metaplasia in the nasal mucosa, decreased body and organ weights, lymphocytosis, and minor alterations in serum and urine chemistries. No ultrastructural evidence of peripheral neuropathy was observed. Except for central neuropathy, many of the adverse effects at 650 ppm were less marked in the 4-week recovery animals. No deaths occurred at 307 ppm, but females had slightly decreased body weight gains, and in both sexes there were minor alterations in hematology, serum chemistry, and urinalysis parameters, which were not present in the 4-week recovery animals. Rats exposed to 101 ppm showed no differences from the control rats. Subchronic exposure to 650 ppm of acetylacetonate vapour causes serious adverse biological effects. Under these study conditions, the minimum-effects concentration was 1277.12 mg/m³, and the no-adverse effects concentration was 420 mg/m³.

Vanadium compounds

Hazard values of the vanadium containing source substances were converted to the target substance vanadium acetylacetonate. The hazard values for vanadium acetylacetonate were calculated as follows:

Effect concentration of vanadium in in source substance (EC (V))

MW (source substance) = 116.98 g/mol

MW (Vanadium) = 50.94 g/mol

ratio of Vanadium in source substance = n* 50.94 / MW (source substance)

EC (V) = EC(source substance) x ratio of vanadium in source substance

Effect concentraion of target substance vanadium acetylacetonate (VAA)

MW V in VAA = 50.94 g/mol

MW VAA = 348.27 g/mol

EC (VAA) in target = EC (V) in source / 50.94 x 348.27

Sub-acute study (NTP, 2002)

Rats

Groups of five male and five female rats were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 2, 4, 8, 16, or 32 mg/m3 by inhalation, 6 hours per day, 5 days per week for 16 days. Three males in the 32 mg/m3 group died before the end of the study. Mean body weights of males and females exposed to 8 mg/m3 or greater were less than those of the chamber controls. Clinical findings included rapid respiration and hypoactivity in rats exposed to 16 or 32 mg/m3. Relative lung weights of 4 mg/m3 or greater males and 2 mg/m3 or greater females were significantly greater than those of the chamber controls. Lavage fluid analysis indicated an inflammatory response in the lung that was either directly mediated by vanadium pentoxide or was secondary to lung damage induced by vanadium pentoxide exposure.

Mice

Groups of five male and five female mice were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 2, 4, 8, 16, or 32 mg/m3 by inhalation, 6 hours per day, 5 days per week for 16 days. All males exposed to 32 mg/m3 and one 8 mg/m3 male died or were killed moribund before the end of the study. Mean body weights of 16 mg/m3 males and 8 mg/m3 or greater females were significantly less than those of the chamber controls, and the 32 mg/m3 females lost weight during the study. Absolute and relative lung weights of 4 mg/m3 or greater males and all exposed groups of females and liver weights of 16 mg/m3 males were significantly greater than those of the chamber controls. The mediastinal lymph nodes were enlarged in 4, 8, and 16 mg/m3 males and females, and lymphoid hyperplasia was confirmed histologically. Lavage fluid analysis indicated an inflammatory response in the lung that was either directly mediated by vanadium pentoxide or was secondary to lung damage induced by vanadium pentoxide exposure.

The concentrations of 16 and 32 mg/m3 correspond to doses of 61.3 and 122.5 mg/m3 of the target substance vanadium-tris-acetylacetonate.

Sub-chronic study (NTP, 2002)

Rats

Groups of 10 male and 10 female rats were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 1, 2, 4, 8, or 16 mg/m³ by inhalation, 6 hours per day, 5 days per week for 3 months. Seven males and three females exposed to 16 mg/m³ died during the study. Mean body weights were significantly less in males exposed to 4 mg/m³ or greater and in females exposed to 16 mg/m³. Abnormal breathing, thinness, lethargy, abnormal posture, and ruffled fur were observed in rats exposed to 16 mg/m³.

Hematology results indicated that exposure of rats to vanadium pentoxide induced a microcytic erythrocytosis in males and females. Absolute and relative lung weights were significantly greater for 4 mg/m³ or greater males and females than for the chamber controls as were the relative lung weights of 2 mg/m³ males. The estrous cycle of females exposed to 8 mg/m³ was significantly longer than that of the chamber control group, and the number of cycling females in the 16 mg/m3 group was reduced. The incidences of several nonneoplastic lesions of the lung and nose were significantly increased in males and females exposed to 2 mg/m³ or greater. Data from pulmonary function analyses indicated that a restrictive lung disease was present in male and female rats exposed to 4 mg/m³ or greater, while an obstructive lung disease was present only in the 16 mg/m³ groups.

Mice

Groups of 10 male and 10 female mice were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 1, 2, 4, 8, or 16 mg/m3 by inhalation, 6 hours per day, 5 days per week for 3 months. One male exposed to 16 mg/m3 died before the end of the study. Mean body weights of 8 and 16 mg/m3 males and 4 mg/m3 or greater females were significantly less than those of the chamber controls. Absolute and relative lung weights of males and females exposed to 4 mg/m3 or greater were significantly greater than those of the chamber controls. The epididymal spermatozoal motility of males exposed to 8 or 16 mg/m3 was significantly decreased. Some mice exposed to 2 or 4 mg/m3 had inflammation of the lung, and all mice exposed to 8 or 16 mg/m3 had inflammation and epithelial hyperplasia of the lung.

A NOAEL of 1 mg/m3 can be derived for rats and mice from these two 13-week studies with vanadium pentoxide. The NOAEL of 1 mg/m3 corresponds to a concentration of 3.8 mg/m3 when converted to the target substance vanadium-tris-acetylacetonate.The effect concentrations 2 and 4 mg/m3 correspond to 7.7 and 15.3 mg/m3 vanadium-tris-acetylacetonate.

Chronic study (NTP, 2002)

rats

Groups of 50 male and 50 female rats were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 0.5, 1, or 2 mg/m³ by inhalation, 6 hours per day, 5 days per week for 104 weeks. Survival and body weights of males and females were generally similar to those of the chamber controls. Mean body weights of females exposed to 2 mg/m³ were less than those of the chamber controls throughout the study. Alveolar/bronchiolar neoplasms were present in exposed groups of male rats, and the incidences often exceeded the historical control ranges. Alveolar/bronchiolar adenomas were present in 0.5 and 1 mg/m³ females; one 2 mg/m³ female also had an alveolar/bronchiolar carcinoma. The incidence of alveolar/bronchiolar adenoma in the 0.5 mg/m3 group was at the upper end of the historical control ranges. Nonneoplastic lesions related to vanadium pentoxide exposure occurred in the respiratory system (lung, larynx, and nose) of male and female rats, and the severities of these lesions generally increased with increasing exposure concentration.

0.5, 1 and 2 mg/m³ vanadium pentoxide correspond to 1.9, 3.8 and 7.7 mg/m³ vanadium-tris-acetylacetonate.

mice

Groups of 50 male and 50 female mice were exposed to particulate aerosols of vanadium pentoxide at concentrations of 0, 1, 2, or 4 mg/m³ by inhalation, 6 hours per day, 5 days per week for 104 weeks. Survival of 4 mg/m³ males was significantly less than that of the chamber controls. Mean body weights of 4 mg/m³ males and all exposed groups of females were generally less than those of the chamber controls throughout the study, and those of males exposed to 2 mg/m³ were less from week 85 to the end of the study. Many mice exposed to vanadium pentoxide were thin, and abnormal breathing was observed in some mice, particularly those exposed to 2 or 4 mg/m³. The incidences of alveolar/bronchiolar neoplasms were significantly increased in all groups of exposed males and females. Nonneoplastic lesions related to vanadium pentoxide exposure occurred in the respiratory system (lung, larynx, and nose) of male and female mice, and the severities of these lesions generally increased with increasing exposure concentration. Bronchial lymph node hyperplasia was present in many exposed females.

1, 2 and 4 mg/m³ vanadium pentoxide correspond to 3.8, 7.7 and 15.3 mg/m³ vanadium-tris-acetylacetonate.

Carcinogenicity

Under the conditions of this 2-year inhalation study, there was some evidence of carcinogenic activity* of vanadium pentoxide in male F344/N rats and equivocal evidence of carcinogenic activity* of vanadium pentoxide in female F344/N rats based on the occurrence of alveolar/bronchiolar neoplasms. There was clear evidence of carcinogenic activity* of vanadium pentoxide in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms.

Exposure to vanadium pentoxide caused a spectrum of nonneoplastic lesions in the respiratory tract (nose, larynx, and lung) including alveolar and bronchiolar epithelium hyperplasia, inflammation, fibrosis, and alveolar histiocytosis of the lung in male and female rats and mice and an unusual squamous metaplasia of the lung in male and female rats. Hyperplasia of the bronchial lymph node occurred in female mice.

(*) -Clear evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a dose-related (i) increase of malignant neoplasms, (ii) increase of a combination of malignant and benign neoplasms, or (iii) marked increase of benign neoplasms if there is an indication from this or other studies of the ability of such tumors to progress to malignancy.

-Some evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a chemical-related increased incidence of neoplasms (malignant, benign, or combined) in which the strength of the response is less than that required for clear evidence.

-Equivocal evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing a marginal increase of neoplasms that may be chemical related.

-No evidence of carcinogenic activity is demonstrated by studies that are interpreted as showing no chemical-related increases in malignant or benign neoplasms.

-Inadequate study of carcinogenic activity is demonstrated by studies that, because of major qualitative or quantitative limitations, cannot be interpreted as valid for showing either the presence or absence of carcinogenic activity.

Justification for classification or non-classification

Based on the available data, vanadium-tris-acetylacetonate is classified for specific target organ toxicity (STOT-repeated exposure) Category 2 (H373) in accordance with Regulation (EC) No 1272/2008. The NOAEC for rats and mice derived in a subchronic study with vanadium pentoxide corresponds to 0.0038 mg/L vanadium-tris-acetylacetonate. This value is lower than the reference value for category 1 classification for vapours of ≤ 0.02 mg/L as specified in Regulation (EC) No 1272/2008, Annex 1, table 3.9.2. Therefore, the registered substance is classified as STOT RE Category 1 (H372).

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